Octahedral tilt independent magnetism in confined GdTiO$_3$ films

TL;DR

This study shows that ferrimagnetism in GdTiO$_3$ films persists despite the suppression of octahedral tilts when confined between SrTiO$_3$ layers, indicating tilt-independent magnetism.

Contribution

It demonstrates that GdTiO$_3$ ferrimagnetism remains stable even as octahedral tilts are suppressed in confined thin films, revealing tilt-independent magnetic behavior.

Findings

Ferrimagnetism persists despite tilt suppression.

Magnetic dead layers form at interfaces.

Core magnetic moment is weakly affected by tilt changes.

Abstract

Polarized neutron reflectometry measurements are presented exploring the evolution of ferrimagnetism in GdTiO$_3$ films as they are confined between SrTiO$_3$ layers of variable thicknesses. As GdTiO$_3$ films approach the thin layer limit and are confined within a substantially thicker SrTiO$_3$ matrix, the TiO$_6$ octahedral tilts endemic to GdTiO$_3$ coherently relax toward the undistorted, cubic phase of SrTiO$_3$. Our measurements reveal that the ferrimagnetic state within the GdTiO$_3$ layers survives as the TiO$_6$ octahedral tilts in the GdTiO$_3$ layers are suppressed. Furthermore, our data suggest that a magnetic dead layer develops within the GdTiO$_3$ layer at each GdTiO$_3$/ SrTiO$_3$ interface. The ferrimagnetic moment inherent to the core GdTiO$_3$ layers is negligibly (in models with dead layers) or only weakly (in models without dead layers) impacted as the octahedral tilt angles are suppressed by more than 50$\%$ and the $t_{2g}$ bandwidth is dramatically renormalized.